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From Kiran Ayyagari <kayyag...@apache.org>
Subject Re: Another potential improvement
Date Wed, 31 Jul 2013 20:43:47 GMT
On Thu, Aug 1, 2013 at 1:59 AM, Emmanuel L├ęcharny <elecharny@gmail.com>wrote:

> There is some room for improvement in the encoded metod too...
>
> When we process a search, we write the result to the client. The result
> is a plain java object, and we have to encode it as a BER encoded ASN1
> message. In order to do that, we compute the size of the buffer we will
> need to use to store the message, then we allocate this buffer, and fill
> it.
>
> As we can see, it's a three step process, but the allocation itself is
> just 3% of the encoding time.
>
> The compuatio of the buffer isze is itself the most exepnsive part, and
> I believe that it's probably a waste : we don't care to know the exact
> size of the needed buffer, as soon as we have a big enough buffer we can
> use to store the response. At this point, if we associate a
> pre-allocated buffer to the ThreadLocal, we could reuse it over and over
> to store the data we will produce during the encoding phase. if the
> buffer is too small, then we can catch the exception, create a bigger
> buffer, and resume the operation (this is a worse case scenario, which
> is not frequent if the bffer is correctly sized to be big enough for
> most of the use case).
>
> Haing a 64Kb ByteBuffer pre-allocated and stored in the ThreadLocal is
> most certainly the best way to slash the time it takes to encode a message.
>
> We can do what we alredy have done with the Dn parsing : keeping what we
> have for when we get an exception because the buffer is too small, and
> for the common use case, go on with a simpler encoding where we don't
> compute the length of the buffer.
>
> The gain could be intersting!
>
> Note : this is not that simple : to save some CPU, we store the result
> of String -> byte[] conversions done during the computeLength() phase.
> Those conversions will have to be done in the simplified method. This
> will limit a bit the expected gain. OTOH, we will save us the creation
>
+1, this should cut down the overhead by half at least, cause we are
avoiding the
byte[] conversion twice

> of many temporary lists we use to store those pre-converted elements.
>
> --
> Regards,
> Cordialement,
> Emmanuel L├ęcharny
> www.iktek.com
>
>


-- 
Kiran Ayyagari
http://keydap.com

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